Disk drive devices using various kinds of disks, such as an optical disk, a magneto-optical disk, and a flexible magnetic disk, have been known in the art. In particular, a hard disk drive (HDD) has been widely used as a storage device of a computer and has been one of indispensable disk drive devices for current computer systems. Moreover, the HDD has found widespread application such as a removable memory used in a moving image recording/reproducing apparatus, a car navigation system, a cellular phone, or a digital camera, as well as the computer, due to its outstanding characteristics.
Such all HDD requires high reliability. Therefore, a step of inspecting a surface of the magnetic disk for defects is required in its manufacturing process. As an example of the inspection of the magnetic disk, there is a test where the HDD itself detects defects of the magnetic disk therein. For example, the HDD writes data on each data track of the magnetic disk and reads the written data for locating defects in the magnetic disk. This test is performed over the whole surfaces of the respective recording surfaces of the HDD. The detected defect sectors are registered in a defect table. Then, the HDD does not access the defect sectors recorded in the defect table but skip them.
The HDD is specified to be used within a specific temperature range and a specific altitude (air pressure) range in its specification. A clearance between a head and a disk (a gap between a head and a disk) changes according to the ambient temperature and the altitude (air pressure). Specifically, the clearance increases as the temperature becomes lower, and decreases as the altitude becomes higher. An inspection by the HDD under a specific condition may cause overlooking any defects possibly appearing under at different condition. Therefore, the inspection for detecting defects of the magnetic disk is preferably performed according to the variable clearance. For example, changing the fly-height of a head slider is disclosed in Japanese Patent Publication No. 6-309636 (“Patent Document 1”), by performing the defect inspection of the magnetic disk in an atmosphere under a reduced pressure.
As described above, changing the temperature or the air pressure has conventionally been required for the defect detection inspection of the magnetic disk under various clearance conditions. However, because the defect detection inspection of the magnetic disk is carried out while the HDD is placed inside a chamber, the tests involving changing temperature or air pressure require much time and equipment.